Help “Minimize the Degree” of Weeds and Algae – Your Do’s and Don’ts

While it’s true that most lakes and ponds will naturally have weeds and algae, there are some things you can do to minimize the degree to which they flourish. Most of the suggestions we will provide you with below relate to controlling the amount of nutrients that get into your lake or pond through some obvious, and other less obvious ways. Following these suggestions can have a dramatic effect on controlling the growth of weeds and algae in your lake or pond, so you may want to print this page out for others on your lake or pond.

Do's

  • When you plant or replant your lawn, use a seed mixture with a high percentage of fescue grass. It requires much less fertilizer which acts as a nutrient for the weeds and algae in your lake.
  • Leave grass clippings on the lawn. They return nutrients to the lawn.
  • Avoid fertilizing your lawn or garden. If you must fertilize, use a product with little or no phosphorus such as 23-0-6, 30-4-4 or 26-4-4. Lake weeds and algae are good sources of nutrients for your garden.
  • Use lake water for watering your lawn or garden. Water only when necessary.
  • Rake your lawn (leaves) away from the lake. Leaves contain large amounts of nutrients.
  • Start a compost pile using leaves and weeds raked from the lake. This compost is excellent for your garden and landscape plants.
  • Maintain your septic system regularly. The septic tank should be pumped and inspected every one to three years, depending on usage.
  • Reduce the amount of water used in your home by adding water dams to your toilet tank and installing faucet aerators and low-flow shower heads. This helps your septic system operate more efficiently, preventing sewage flow into your lake.
  • When feasible, plant a shoreline (20 feet wide) of shrubs, bushes and trees. These plants utilize phosphorus and nitrogen and act as a buffer zone or filter before groundwater and runoff pass into the lake.
  • Be sure there is proper drainage on and near your lot so that erosion will not take place.
  • If you must use fertilizers, try to find a good liquid fertilizer as these are far less likely to run off into lake waters and are also more likely to be absorbed and retained in the soil.

Don'ts

  • Drain any type of sewage into the lake.
  • Burn leaves near the shoreline. Burning turns the leaves into instant fertilizer which is easily washed into the water.
  • Destroy the soil holding vegetation on the shoreline. These plants prevent erosion.
  • Clean fish on the dock and throw remains into the water.
  • Alter the natural shoreline unless state approved by the Department of Natural Resources.
  • Feed ducks or geese from your dock. Plenty of natural food is available in the lake. Ducks and geese may pass on swimmer’s itch and leave significant amounts of “natural” fertilizer.
  • Use a garbage grinder in your kitchen. Ground-up food contributes to septic system problems and may add nutrients to the lake.
  • Use cleaning products containing phosphates. In Michigan, laundry detergents containing phosphates are banned, but read the label on other products to be sure they do not contain them.
  • Harm your septic drain field by adding fill, planting deep rooted trees nearby, or driving a vehicle over it.

More on Hazards of Nutrients

Dr. Darryl Warncke, professor of soil fertility at Michigan State University cites nitrogen and phosphorus as the two main nutrients that can enter a lake and stimulate aquatic plant growth. He says that aquatic plant growth is a key player in eutrophication, the natural aging process every lake is undergoing. The natural aging process is supposed to take several thousand years, but recent human actions, particularly the use of nitrogen and phosphorus based fertilizers, has accelerated eutriphication the point that some lake residents have been able to see their lake’s water quality deteriorate.

“Phosphorus based fertilizers are actually more of a problem than a fertilizer with more of a nitrogen base,” Warncke says. “Phosphorus is the biggest contributing factor to stimulation of aquatic plant growth. Many aquatic plants have the ability to absorb dissolved nitrogen that’s already in the lake water.” It’s important for lakefront property owners and residents to minimize the phosphorus inputs into the lake caused by fertilizing lawns, according to Warncke. He says that in many instances soil already has enough phosphorus to support a green lawn, and that applying phosphorus based fertilizers can be a waste of time, energy, money and a potential threat to the lake.

“I strongly urge lakefront residents to take a sample of their soil and have it analyzed for its phosphorus content before using a phosphorus based fertilizer,” Warncke says. “Analyzing the phosphorus content of the soil can determine whether this nutrient is needed at all, or at what levels it’s needed to maintain a healthy lawn. In many cases, homeowners over-apply phosphorus based fertilizers or unnecessarily apply these fertilizers.” Lakefront residents who want their soil analyzed for nitrogen and phosphorus concentrations can send soil samples to the Soil and Testing Laboratory, Room 81, Plant and Soil Sciences Building, Michigan State University, East Lansing. Michigan 48824. For more information, call the soil testing lab at (517) 355-0218.

More on Maintaining your Septic System

If you live on shoreline property, maintaining your septic system requires more care and work than maintaining similar systems in other places. That’s because soil and water conditions near the shoreline may make the system less efficient in treating waste, which could, in turn, cause harmful pollutants to get into your lake, stream or pond.

Because septic systems on shoreline property are often close to the water and are sometimes saturated during high periods, they are very likely to leak wastes to lakes and streams. Also, when shorelines erode, the distance between the septic system and the shoreline gets shorter and shorter, making it more likely that liquid waste could move horizontally through the soil to the bank and then quickly over the surface to the water. This pollution can happen even though your system appears to be working properly and complies with local health department codes.

septic diagram

Nutrients (especially phosphates) from leaky septic systems play a major role in causing excessive weed and algae growth in lakes and ponds. Just a small amount of additional phosphates in a lake or pond can make a huge difference in the amount of aquatic weeds that grow during the spring and summer. Excessive weed growth, in turn, affects the ability of fish to grow and could even result in large fish kills in summer or winter. Too many weeds and algae make the water less enjoyable to use. Liquid wastes from your septic system that reach the water increase the chance that swimmers near your shore could catch a variety of diseases and ailments, some serious, that are associated with these waters.

There are numerous symptoms for telling if waste from your system is reaching surface water.

  • Excessive weed or algae growth in the water near your shore.
  • An increase in infections or illnesses associated with swimming in the area.
  • Unpleasant odors, soggy soil or liquid waste flow over the land surface.
  • Health department test results indicate the presence of biological contamination.
  • Indicator dye put into your septic tank reaches lakes or ponds.

There are a variety of things you can do to help prevent the problems associated with having a septic system near shoreline areas.

  • Regularly pump and maintain your septic system.
  • Conserve water in your home.
  • Redirect surface water flow away from your absorption field.
  • Plant a greenbelt between your absorption field and the shoreline.
  • Participate in a community sewage system or alternative disposal methods, if available.
  • If your constructing a new home, construct the septic system as far away from the shoreline as possible.